there's a big difference between genes that influence duration of life and genes that are there specifically for the purpose of causing us to age or to die. the ladder cannot occur, the former must occur. >> in what sense is evolution the culprit? >> well, our genes evolved tens of thousands of years ago, conditions were very different. there was not a survival advantage for the species for people to live a very long time so long, longevity, long life-spans were not selected. >> you mean because of the food opportunities and the lean hunting seasons? >> there was limited physical resources, limited food, so it's difficult to say that death was selected for but i think we can say that long life was not an advantage. so evolutions did not select us to live a long time. >> does d%ath make sense from a darwinian perspective? >> there have been arguments that people dying, you know, after child-rearing would free up resources for the young. we don't have proof of that. i think what we can say is that long life was not selected for because there was no evolutionary advantage to reproduction for lo